The disclosed embodiments relate to contacts that conduct current, and in particular, contacts that experience repulsion forces when mating as a result of the amount of current conducted by the contacts.
Circuit breakers are used to protect equipment from overcurrent situations caused, for example, by short circuits or ground faults in or near such equipment. In the event an overcurrent condition occurs, electrical contacts within the circuit breaker will open, stopping the flow of electrical current through the circuit breaker to the equipment. Circuit breakers may be designed for high quiescent currents and high withstand currents. To maintain a high withstand current rating, the contacts must be locked closed at the current withstand rating and be able to withstand the large electrodynamic repulsion forces generated by the current flow.
The variety of constructions of multipole circuit breakers include blow open and non-blow open contact arms, overcentering and non-overcentering contact arms, single contact pair arrangements with the contact pair at one end of a contact arm and a pivot at the other end thereof, double contact pair arrangements (referred to as rotary breakers) with a contact pair at each end of a contact arm and a contact arm pivot intermediate (typically centrally located between) the two ends, single housing constructions with the circuit breaker components housed within a single case and cover, and cassette type constructions (referred to as cassette breakers) with the current carrying components of each phase housed within a phase cassette and each phase cassette housed within a case and cover that also houses the operating mechanism. Multipole circuit breakers are generally available in two, three, and four pole arrangements, with the two and three pole arrangements being used in two and three phase circuits, respectively. Four pole arrangements are typically employed on three phase circuits having switching neutrals, where the fourth pole operates to open and close the neutral circuit in a coordinated arrangement with the opening and closing of the primary circuit phases.
While conventional circuit breakers are considered suitable for their intended purpose, the art of circuit breakers may be improved by providing a module breaker design having improved operation life and durability while avoiding falling off or movement of the moving runners relative to its respective contact during, for example, short circuit.